Systems for automating the storage and distribution of containerized goods in warehousing and manufacturing facilities have been developed to reduce the expense and errors associated with manual storage and distribution. Automated storage and distribution systems, such as that described in U.S. Pat. No. 4,621,745, can improve warehouse and manufacturing operation efficiency and inventory management.
U.S. Pat. No. 4,621,745 discloses a container storage and dispensing assembly for use in an automated storage and distribution system. The assembly includes two opposing stacks of vertically staggered shelf assemblies. The shelf assemblies receive containers at the top of the stacks and distribute the containers in zigzag fashion downward through the stacks to a dispensing location at the bottom of the stacks.
Each shelf assembly is mounted relative to a support structure to pivot between an upwardly tilted receiving position, a substantially horizontal storage position, and a downwardly tilted discharge position. In operation, a shelf assembly in the upwardly tilted receiving position receives a container from a next higher shelf assembly that is in the downwardly tilted discharge position. The receiving shelf assembly pivots downwardly under the weight of the container and locks in the horizontal storage position if the next lower shelf assembly is not in the receiving position.
The next lower shelf assembly assumes the receiving position when it is empty. The upper shelf assembly is unlocked from the storage position by the upward movement of the next lower shelf assembly, and is thereby permitted to pivot downwardly to the discharge position to transfer the container to the next lower shelf assembly. In this manner, the containers move downwardly through the stacks in sequential fashion until the lowermost shelf assemblies are filled with containers, and advance sequentially as containers are dispensed from the bottom of the stacks.
During operation, a transferred container can topple or lodge between shelf assemblies if the receiving shelf assembly is not prevented from pivoting downwardly from the receiving position before the container is completely disposed on the receiving shelf surface. Accordingly, the descent of the receiving shelf assembly should be delayed until the container is fully received.
Static friction between a stored container and the underlying shelf surface can sometimes prevent the container from sliding off the shelf assembly during a discharge operation. The friction can be offset by increasing the downward angle of the downwardly tilted discharge position to provide a steeper discharge slope. However, increasing the discharge tilt angle reduces the quantity of shelf assemblies that can be arranged in a stack of specified height. It would be desirable to overcome this friction without increasing the discharge tilt angle of the shelf assembly.